Does exercising on an empty stomach burn more fat?

If you have spent a decent amount of time talking to different people about the best way to lose weight, you may have heard the advice…

“Do your cardio in the morning, before you eat”

The effects of exercising in the morning

The basic idea behind this well known theory, is that when you haven’t eaten all night and are in “fasting mode”, all the calories you burn in a workout will directly come from your body fat stores, because you cannot use previously eaten food as energy. Physiologically this is a great approach for extra fat loss; however, there is one more question I think you need to ask.

“Besides body fat, what is another source our bodies can burn for energy?”

The answer is MUSCLE, and this is never a good thing trust me, no matter how bad you want weight loss, you do not want muscle loss. Too intense of cardio in the morning can burn away hard-earned muscle, but that does not mean this method is useless. There is a relatively simple way to get around the issue, just to be safe eat a small amount of protein or 5g of BCAAs and 5g Glutamine in a shake prior to exercise.

True, a lot of the protein you eat prior is going to be burned off as energy for the workout; however, the positive effect of it preserving muscle tissue is well worth it in my opinion. Keep in mind however, during this workout you will have no recently eaten carbohydrates and fats to use as energy, so you may find it harder to keep the intensity as high as a mid-day workout.

Why your body burns more fat in the morning?

Nevertheless, I think a common misconception needs to be cleared up before we discuss this method of cardio further.

Many people believe the reason you burn the fat directly from fat stores upon waking is that your body is in a glycogen-depleted state. However, this is not the case, you see when you go to sleep, after around 30 minutes, you enter the deep sleep phase, during this phase, 95%+ of the calories you burn are from free fatty acids because it is such a low intensity period.

Therefore, since the primary source of energy your body uses during sleep is fatty acids, experts agree when you are awake you will not have to mobilize fatty acids to be used for energy; therefore they are far more likely to be used as energy first.

In the end you need to understand when dealing with our bodies, things are never simple and no one can tell you one way is 100% better then the other. There are far too many factors involved to justify saying, “Morning cardio is FAR superior then mid day cardio”. However I do think it is useful and do recommend it be used, but rather as a way to split your cardio in half.

Split your cardio throughout the day for optimum results

For example if you normally do 40 minutes of cardio daily, I recommend upon waking you eat a small amount of protein, then do 20 minutes of cardio. Continue as normal and do the last 20 minutes mid day, research has shown for years that splitting your cardio up into multiple sessions is very effective in squeezing out more fat loss due to EPOC.

EPOC or Excess Post-Exercise Oxygen Consumption

EPOC or Excess Post-Exercise Oxygen Consumption means our workouts have an “after burn effect”, meaning immediately after a workout we are still burning more calories then if we never worked out. This elevated state of calorie burning begins to diminish soon after a workout however, although some experts claim EPOC does not have as big effect on fat loss as some people say; studies have shown it does help. Furthermore, everyone I have recommended it to has seen improved results over one cardio session a day. It may not be a huge difference, but every inch counts.

That is what long-term weight loss is about, like almost anything in life, getting healthy is a game of inches. Saving an extra 100 calories a day may not seem like a lot but that is 36,000 calories a year, which is roughly 10 pounds of fat saved!

Therefore, I urge you to take any advantage you can get in your day-to-day training, before those extra inches you did not go end up being a few extra inches around your waist.

Nevertheless, most of all I wish you good luck in your health goals, becoming healthier is the greatest step you can take towards true happiness. Money can buy many things, but it cannot buy good health once you lost it, fitness is the closest thing we have to the fountain of youth.